An external device, such as an external case, may be used with an electronic device to personalize the electronic device and provide improved shock resistance, protection, and functions to the electronic device. For example, in some cases, it may be desirable to include additional connectors, adaptors or convertors in the external case for connecting additional devices in or outside the external device to the electronic device. Leather, fabric, or other non-moldable material may be used to cover the external device to improve the feel and appearance of the external device. However, making an overlay cover for the external device using materials that are not suitable for molding or three-dimensional (3-D) printing may be difficult, and may create undesirable features, such as wrinkles at corners (especially round corners), that could affect the feel and appearance of the external device.